A two-way Hybrid Fiber-Coaxial (HFC) cable system includes a Cable Modem Termination System (CMTS). The CMTS converts digital signals into a modulated Radio Frequency (RF) signal which is carried over optical fiber and coaxial lines to cable modems at different subscriber locations. The cable modems demodulate the RF signal and feed the demodulated digital data to a computer. On a return path, the operations are reversed. Digital data is fed to the cable modem which modulates the digital data with an RF signal. The CMTS demodulates the RF signal received from the cable modem and transmits the digital data to an endpoint over a Wide Area Network (WAN).
Flap lists have been used to identify and track cable modems that experience intermittent connectivity problems. A Media Access Control (MAC) layer keeps a miss count that reflects the number of times the CMTS fails to receive a polling message from the cable modem during an allotted time slot. The miss count is tabulated in a form that can be analyzed to determine failure characteristics of the cable television plant.
The cable TV industry has been upgrading its signal distribution and transmission infrastructure. For example, Data Over Cable Service Interface Specification (DOCSIS) 3.0 introduces the concept of multiple bonded RF channels to the legacy DOCSIS architecture. Unlike single channel devices, the multi-channel/wideband devices will not go offline or lose all connectively when some of the bonded channels fail. Thus, existing cable modem failure analysis schemes may not contain complete and pertinent data for these wideband related failures.